This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-103119 filed on Apr. 2, 2001.
The present invention relates to an engine starter system for starting an engine.
In a conventional engine starter system, when an engine key switch is turned on, a solenoid switch generates magnetic power with its exciting winding being energized. When a plunger, moved by the magnetic power, closes contact points for a motor of the starter, a hitting sound is generated. In order to reduce the hitting sound, a large current (rush current) is required to be restricted when the key switch is turned on. Therefore, a current restricting device is connected to the exciting winding in series, thereby restricting a current flowing into the exciting winding by the current restricting device.
However, the output of the starter is reduced due to a voltage drop at the current restricting device. Further, when the capacity of a battery is reduced and the voltage of the battery is reduced by energizing the motor, the operation of starting the engine cannot be sometimes maintained due to the voltage drop at the current restricting device. Furthermore, a low-cost current restricting device is desired to be used in the engine starter system for reducing the production cost of the engine starter system.
The present invention therefore has an object to provide an improved engine starter system.
Further, the present invention has an object to provide an engine starter system, which can surely start an engine even when the capacity of a battery is reduced.
According to the present invention, an engine starter system includes a first energizing circuit having a current switching device, a second energizing circuit having a relay, and an electronic control circuit for controlling the operations of the current switching device and the relay. The current switching device and a motor armature are connected in series, and the relay contact points and the armature are connected in series. The first energizing circuit energizes the armature by turning on the current switching device, and the second energizing circuit energizes the armature by closing the relay contact points.
Accordingly, the armature can be energized by suitably changing any one of the first and second energizing circuits. For example, when an engine is started, the armature is energized by turning on and off the current switching device with a varying duty ratio, so that the current flowing through the armature is controlled to increase gradually for reducing a rush current. When a large current is required, the armature is energized by closing the relay contact points thereby shorting the switching device.